XSS in Parse-Community Parse-Server
CVE-2026-31868
Parse Server is an open source backend that can be deployed to any infrastructure that can run Node.js. Prior to 9.6.0-alpha.4 and 8.6.30, an attacker can upload a file with a file extension or content type that is not blocked by the default configuration of the Parse Server fileUpload.fileExtensions option. The file can contain malicious code, for example JavaScript in an SVG or XHTML file. When the file is accessed via its URL, the browser renders the file and executes the malicious code in the context of the Parse Server domain. This is a stored Cross-Site Scripting (XSS) vulnerability that can be exploited to steal session tokens, redirect users, or perform actions on behalf of other users. Affected file extensions and content types include .svgz, .xht, .xml, .xsl, .xslt, and content types application/xhtml+xml and application/xslt+xml for extensionless uploads. Uploading of .html, .htm, .shtml, .xhtml, and .svg files was already blocked. This vulnerability is fixed in 9.6.0-alpha.4 and 8.6.30.
Vulnerability class: XSS (Cross-Site Scripting)
Published · last modified .
CVSS v3 metric
CVSS v3 base score 6.1 (Medium). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N.
EPSS exploit prediction
EPSS: 0.003 (23.3th percentile), scored .
Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 23rd percentile — 23.3% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.
EPSS over last 30 days · oldest: 0.002 · newest: 0.003 · change: +0.001
Affected products
- Parse-Community Parse-Server — versions >= 9.0.0 < 9.6.0-alpha.4, < 8.6.30
- Parseplatform Parse-Server — versions 9.6.0
Weakness classification (CWE)
References
- github.com/parse-community/parse-server/security/advisories/GHSA-v5hf-f4c3-m5rv (Patch, Mitigation, Vendor Advisory)
- github.com/parse-community/parse-server/releases/tag/8.6.30 (Product, Release Notes)
- github.com/parse-community/parse-server/releases/tag/9.6.0-alpha.4 (Product, Release Notes)
Frequently asked questions
- What is CVE-2026-31868?
- CVE-2026-31868 is a medium-severity vulnerability in Parse-Community Parse-Server, classified under Cross-site Scripting. CVSS score: 6.1/10. Published 2026-03-11.
- How severe is CVE-2026-31868?
- Medium severity. CVSS v3 base score is 6.1 out of 10.